This invention relates to a character segmentation method, and particularly to the character segmentation method which optically reads and recognizes postal address information including postal code, city name and state name.
FIG. 1 shows a known optical character reader for reading the postal code on postal material comprising: a scanner 1, an image signal processing unit 3, a character segmentation unit 4, and a character recognition unit 5. Scanner 1 optically scans the printed area representing the postal code information and produces a scanning signal. The scanning signal is then transformed into electric pattern signals by an image signal processing unit 3. The transformed electric signals, representing postal code signals, are then transmitted to a character segmentation unit 4 which detects the characters and segments of the postal code, and transmits this information to a character recognition unit 5. The character recognition unit recognizes the character of the code by using a known technique, for example, by comparing the characters with standard patterns. The character segmentation unit of the prior art detects and segments only the postal code information.
However, in recent years, it has become desirable, in postal processing, that both the postal code and its related information (e.g., the city name and the state name) be read and checked to determine if the postal code accurately corresponds to the related information. In this way, errors in the postal code can be detected.
In using the prior art system wherein each character is detected and segmented respectively, character recognition processing after the character segmentation becomes very complicated. The complication is due to the inability of the system to distinguish the different types of blocks of characters. Because the city name and the state name are alphabetical and the postal code is numerical, the standard pattern corresponding to these distinct kinds of information must be separately selected. Consequently, the character recognition process becomes very complicated.